9.Models
Air drives have these advantages:
a)Improved mixing due to back and forth motion of the blades.
b)No EMF (Electro Magnetic Force) feedback to the processor from electrical demands of the motor resulting, the results in less processor problems.
c)Less electronic parts on the board, parts that are vulnerable to failure from
d)Inherent safety for plant personnel due to the more controlled, more limited torque of an air drive compared to an electric motor drive. A correctly sized electric motor can deliver 10 times the normal design and operating torque when stalled. In spite of interlocks, this presents a potential safety hazard.
If you are having mix problems with air drives, be sure the blades moves a full 270 degrees (3/4 turn) with each sweep. If they do not, try the following:
a)Increase the air pressure. If the gauge pressure drops more then 5 pounds during operation of the blades, the air supply line is too small.
b)Lower the pile in the mix chamber to reduce torque requirements on the mix blade. This is explained above.
c)Increase the MPO parameter from 122 (1/2 second) to 183 (3/4 second) or 244 (1 full second). This allows more time for a full mix blade sweep to occur. You may also want to increase mix time from 10 seconds to 15 or 20 seconds so that, in spite of slower mix blade speed, the same amount of mixing occurs.
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